The Mechanicum are not generally known for their assault units. They're just happy to sit back and lob plasma blasts and other various ordinance at their foes. But that's not to say they don't have units designed to run into enemy formations and just start shredding stuff up. That's exactly what the Mechanicum Ursarax are for, and they're available to order now from Forge World.
Whether you want them to go into battle with power fists or lightning claws, the Ursarax are more than happy to go and get hip-deep in enemy soldiers. And I do mean "happy" since these are Thralls and not Servitors (I.E. - there's some living bits still in there, somewhere).
The kit comes with three models and the options to give them either all power fists or lightning claws. The models fit on 40mm bases (included). Orders are being taken now with shipping to commence next week.